Tar substance on exterior. 2001 Air Nautique.

[Adam Kunes]

I recently pulled my 2001 Air Nautique out of the river for the summer. I used slimy grimy to get off most of the alge. It worked like a champ. There was some residue left behind and I'm not exactly sure what it is. It almost seems to be a tar like substance. The slimy grimy is not doing anything to remove. I've attached 2 photos. Is there anything I can use to get this off? I've tried bug and tar, alcohol, very diluted acid, nothing is working. Any help would be greatly appreciated. Thanks.

Adam

[DanielC]

Try Acetone.
Try Lysol toilet bowl cleaner, the one with hydrochloric acid in the ingredients, mixed 50/50 with hydrogen peroxide.
Wear nitrile gloves with these or most any other hull cleaner. Do not get the toilet bowl cleaner on the trailer.

[scott resick]

Ive seen this before. The Allegheny river is a dump station for all the mills and power plants. I try to pull my boat once a month to clean and reapply BTS. It does seem to help. Slimy Grimmy should take that off. Maybe mix it a little stronger and use a soft brush?